The CTS Turbo 1″ breather filter (rubber base) is designed for use on secondary air injection systems with 1″ slip fit connections. This breather filter is included in our CTS-IT-270 & CTS-IT-300 intake kits on cars that are equipped with secondary air injection (SAI). This air filter can also be used in custom applications when a small breather filter is required, such as for custom catch can kits.